package sdfs.server;

import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.net.ServerSocket;
import java.net.Socket;

public class Rpc {
    /**
     * export service
     *
     * @param service implement
     * @param port  port
     * @throws Exception
     */
    public static void export(final Object service, int port) throws Exception {
        if (service == null)
            throw new IllegalArgumentException("service instance == null");
        if (port <= 0 || port > 65535)
            throw new IllegalArgumentException("Invalid port " + port);
        System.out.println("Export service " + service.getClass().getName() + " on port " + port);
        ServerSocket server = new ServerSocket(port);
        while (true){
            try {
                final Socket socket = server.accept();
                new Thread(() -> {
                    try {
                        try
                        {
                            try(ObjectInputStream input = new ObjectInputStream(socket.getInputStream())) {
                                String methodName = input.readUTF();
                                Class<?>[] parameterTypes = (Class<?>[])input.readObject();
                                Object[] arguments = (Object[])input.readObject();
                                ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());
                                try {
                                    Method method = service.getClass().getMethod(methodName, parameterTypes);
                                    Object result = method.invoke(service, arguments);
                                    output.writeObject(result);
                                } catch (Throwable t) {
                                    output.writeObject(t);
                                } finally {
                                    output.close();
                                }
                            }
                        } finally {
                            socket.close();
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }).start();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /**
     *
     *
     * @param <T> interface
     * @param interfaceClass the class of interface
     * @param host host
     * @param port port
     * @throws Exception IllegalArgumentException，IOException
     */
    @SuppressWarnings("unchecked")
    public static <T> T refer(final Class<T> interfaceClass, final String host, final int port) throws Exception {
        if (interfaceClass == null)
            throw new IllegalArgumentException("Interface class == null");
        if (! interfaceClass.isInterface())
            throw new IllegalArgumentException("The " + interfaceClass.getName() + " must be interface class!");
        if (host == null || host.length() == 0)
            throw new IllegalArgumentException("Host == null!");
        if (port <= 0 || port > 65535)
            throw new IllegalArgumentException("Invalid port " + port);
        //System.out.println("Get remote service " + interfaceClass.getName() + " from server " + host + ":" + port);
        return (T) Proxy.newProxyInstance(interfaceClass.getClassLoader(), new Class<?>[] {interfaceClass},
                (proxy, method, arguments) ->
                {
                    try (Socket socket = new Socket(host, port))
                    {
                        try(ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream()))
                        {
                            output.writeUTF(method.getName());
                            output.writeObject(method.getParameterTypes());
                            output.writeObject(arguments);
                            try (ObjectInputStream input = new ObjectInputStream(socket.getInputStream()))
                            {
                                Object result = input.readObject();
                                if (result instanceof Throwable) {
                                    throw (Throwable) result;
                                }
                                return result;
                            }
                        }
                    }
                });
    }

}
